1. Field of the Invention
This invention relates to arrangements for detecting fault conditions in electronic vehicle controls, and more specifically to arrangements for preserving the identity of fault condition indications.
2. Description of the Prior Art
Increases in the speed, sophistication, and complexity of modern mass transit systems have resulted in a corresponding increase in the complexity of electronic vehicle controls. In the course of operating a rapid transit system which is in use in Dusseldorf, Federal Republic of West Germany, it has been learned that in the event of a malfunction, operating personnel do not possess sufficient technical understanding of the complex electronic control technology to identify a fault condition. Thus, as a result of this lack of understanding of the technology and the fact that such operating personnel must concern themselves with the safety and comfort of the passengers in the event of a malfunction, they are unable to provide to maintenance personnel sufficient information which will enable such maintenance personnel to recognize the fault. Moreover, since some faults are intermittent in nature, or related to the operating temperature of the system, maintenance personnel are not able to efficiently localize the fault after the equipment has been removed from service and brought to the maintenance facility.
Vehicle controls of the type used in the Dusseldorf rapid transit system generally contain a number of monitoring devices which transmit fault signals to one or more vehicle controllers. The outputs of the vehicle controllers are combined so as to form a collective signal which is conducted to the fault indicating device of the vehicle. However, the collective signal and the responsive indication at the fault indicating device are cancelled when the vehicle is shut down, and is therefore not available to maintenance personnel during the course of their examination of the vehicle in the maintenance facility. This arrangement makes the servicing of intermittent fault conditions extremely difficult and time consuming.
In addition to the foregoing, operating personnel are generally confused at the time that a fault situation arises, by the fact that a plurality of fault conditions may be present simultaneously. For example, if a primary fault arises which is of the type which causes automatic braking of the vehicle, a plurality of secondary fault signals may be produced shortly thereafter. One such secondary signal may be produced by a speed detector in the system which may have determined that the braking deceleration is excessive in view of the condition of the track.
Accordingly, it is an object of this invention to provide an arrangement which reduces the time and costs required for finding faults in rapid transit vehicles.
It is a further object of this invention to provide an arrangement which preserves the identity of the source of a fault indicating signal after the vehicle has been removed from service.